This has has a fabric panel in the front and mesh everywhere else so vents well. Because of the solid front, I don't use this hat on hot days, warm days yes it is my go to hat. Although a one size fits all, not as big as the Castelli all mesh version and fits my small brain better. Very comfortable to wear and collects sweat well. I don't wear hats as a fashion statement, but instead to keep the setting sun out of my eyes.
Excellent summer cap, incredible wicking and cooling ability and even helps a bit during rain. Not sure how it will fare in winter with wind protection, but it's not really designed for that use case. Very comfortable and stretchy. Would recommend.